1. Field of the Invention
This invention relates to a method for cutting a diamond, and proportions and brightness of a diamond formed by this cutting method.
2. Related Art
In general, a value of a polished diamond is determined by the 4C's, i.e. Carat (Weight), Clarity (Transparency), Color and Cut. Although these 4C's are important respectively, evaluating of a diamond is generally done by Color, Clarity (Transparency), Cut and Carat (Weight) in the mentioned order.
However, before a diamond cutting method was invented, there had not at all been recognition that a diamond could be a beautiful object. Namely, there had been recognition that a diamond had been a mere hard stone. What caused a diamond which had been recognized before to be a mere hard stone to come to be recognized to be a beautiful thing was development of techniques for brightening the diamond beautifully by cutting the same. Therefore, a diamond cutting method has been considered important.
It can be said that brightness of a diamond can be obtained by cutting the same, and a diamond subjected to an excellent cutting process increases in brightness and glitter. Under these circumstances, stress is laid on a cutting method in a diamond market. Therefore, when beauty of a diamond is taken into consideration, it can also be said that an order of importance for evaluation of the beauty of a diamond is Cut, Color, Clarity (Transparency) and Carat (Weight).
In such a cut evaluation method, proportions, symmetry and a polished condition of a diamond are collectively evaluated, and graduated as a cut grade, which constitutes one of barometers used when a consumer purchases a diamond.
However, a diamond is valuable in itself, so that there is a case where stress is laid more on its dimensions and weight by reducing an area to be cut thereof than on its beauty and glitter shown by cutting the same. This causes proportions of a diamond to be deteriorated in some cases.
Therefore, in recent years, balance of a diamond as a whole has come to be seriously considered, and importance has also been attached to the 4C's+S (Symmetry) in which Symmetry is added to the 4C's mentioned above as important elements for evaluating a diamond.
Thus, since a cut is very important for evaluation of a diamond, techniques for a diamond cutting method has heretofore been studied in various respects. A round brilliant cut and techniques disclosed in JP-A-2000-5993 and JP-U-3078636 have been known. Out of these techniques, the round brilliant cut is famous.
A diamond subjected to a round brilliant cut is a fifty-eight-faced polyhedron, and formed so that rays of light entering the diamond are totally reflected on surfaces of bottom portions thereof and shine beautifully. It is said that this reflected light is dispersed and varies to seven colors.
According to techniques disclosed in JP-A-2000-5993, reference lines are provided a diamond by setting an angle determined by dividing an angle of a circumference of a circle of 360° by a number obtained by multiplying 3 by an integral number thereof. The diamond as a whole is then cut into 65 faces or 86 faces.
According to techniques disclosed in JP-U-3078636, cut surfaces provided on a bottom portion of a pavilion, i.e. cross-shaped cut surfaces are seen from a table surface.
When a diamond is similar to a raw ore thereof, brightness and coloring thereof come to be just as those of a related art diamond, in which there is not variations of an individual diamond. Therefore, new brightness of a diamond has been demanded, and, above all, development of a diamond glittering in a golden color has been expected.
In a diamond cutting method based on techniques for obtaining round brilliant cuts, rays of light entering a diamond are totally reflected from a surface of a bottom portion thereof and glitters beautifully. However, this reflected light is the same as that obtained in a related art diamond cutting method, and this reflected light is unable to express a tone of a gold color.
The invention disclosed in JP-A-2000-5993 is unable to express a tone of a gold color. Since reference lines are provided on a diamond by setting an angle obtained by dividing an angle of a circumference of a circle of 360° by a number obtained by multiplying 3 by an integral number of 3, the diamond is not symmetrical.
The invention disclosed in JP-U-3078636 is not a method of varying a tone of color of a diamond. According to this invention, a cross-shaped cut surface is merely seen from a table surface, and the diamond is not symmetrical.
Therefore, it is an object of the present invention to provide a diamond having excellent proportions, i.e. a diamond substantially symmetrical when the diamond is seen from any positions on upper, side and bottom surfaces thereof with light reflected from a table surface having glitter of a golden color.